A 2p poles axial-flow electric motor includes a stator composed of at least one pair of conductor layers on which the printed phases are arranged in semi-phases.
|
1. A magnetic plural pole (2p) axial-flow electric motor comprising:
a rotor; and
a stator with m phases comprising at least one pair of conductor layers on which conductive tracks constituting the phases of the stator are arranged in semi-phases,
the conductive tracks including current access points, each of the current access points directly connecting the conductive tracks of a corresponding phase of the stator to a source of input current to thereby provide electric current access, for current input from and return to the source of input current, to the conductive tracks of each semi-phase, the current access points being located at an inside end of each semi-phase on an internal edge of the stator,
wherein the current access points are arranged on a same radius of the stator,
wherein two of the current access points of the electric current to the conductive tracks of an individual semi-phase of the at least one pair of conductor layers of the stator are offset relative to each other by a rotation angle,
wherein intrinsic connections connect the semi-phases of each phase together, and
wherein the plural pole (2p) axial-flow electric motor has 2p poles, p being a whole number greater than zero.
2. The magnetic plural pole (2p) axial-flow electric motor according to
3. The magnetic plural pole (2p) axial-flow electric motor according to
the conductive tracks arranged in semi-phases and constituting the m phases of the stator are printed layers located on at least a first pair of conductor layers and on a second pair of conductor layers,
the conductive tracks arranged on the first pair of conductor layers defining a first printed electric circuit,
the conductive tracks arranged on the second pair of conductor layers defining a second printed electric circuit identical to the first printed electric circuit,
the first and second printed electric circuits being connected in series,
4. The magnetic plural pole (2p) axial-flow electric motor according to
5. The magnetic plural pole (2p) axial-flow electric motor according to
6. The magnetic plural pole (2p) axial-flow electric motor according to
radians, where n is the mathematical constant pi and p is the number of poles (p).
7. The magnetic plural pole (2p) axial-flow electric motor according to
radians and connected together by the current access points of the electric current to the semi-phases now opposite, where n is the mathematical constant pi and p is the number of poles (p).
8. The magnetic plural pole (2p) axial-flow electric motor according to
9. The magnetic plural pole (2p) axial-flow electric motor according to
radians, each current access point of the electric current being associated with an end of said semi-phase, where n is the mathematical constant pi and p is the number of poles (p).
10. The magnetic plural pole (2p) axial-flow electric motor according to
radians and connected together by the current access points of the electric current to the semi-phases now opposite, where n is the mathematical constant pi and p is the number of poles (p).
11. The magnetic plural pole (2p) axial-flow electric motor according to
12. The magnetic plural pole (2p) axial-flow electric motor according to
each semi-phase comprises two sets of conductive tracks; and
each set of conductive tracks being arranged in a radial configuration between the internal edge of the stator and an external edge of the stator, such that the electric current of a set of conductive tracks of a semi-phase flows from the internal edge of the stator towards the external edge of the stator and the electric current of the other set of conductive tracks of said semi-phase flows from the external edge of the stator towards the internal edge of the stator.
13. The magnetic plural pole (2p) axial-flow electric motor according to
radians, where n is the mathematical constant pi and p is the number of poles (p).
14. The magnetic plural pole (2p) axial-flow electric motor according to
15. The magnetic plural pole (2p) axial-flow electric motor according to
|
The present invention relates to an axial-flow electric motor.
An electric motor is a device which transforms electrical power into mechanical power. The description will be limited to rotating machines. Those skilled in the art could easily transpose the invention to linear machines.
An electric motor is composed of two parts: a rotating part called a rotor and a fixed part called a stator. It is the torque developed between the stator and the rotor which causes rotation of the rotor and provides mechanical power to the driven device.
Electric motors have many applications in industry and in public products such as a washing machine or a quartz watch. One of these applications is propulsion of electric vehicles.
In the case of a brushless motor, the control electronics 10 adapt the phase of the current injected into the motor 12 so that it is locked onto the rotation phase of the rotary magnetic field created by the rotor. An optical position sensor 15, or Hall effect sensor for example, connected to the control electronics 10 can be used to measure the angle of rotation of the rotor relative to the stator, this measurement being integrated into the control loop.
Those skilled in the art know that there are many possible combinations of one or more batteries, one or more electric motors with one or more transmissions and one more motorised wheels for producing such a device.
In some cases the transmission can be omitted by integrating the electric motor 22 into the motorised wheel as illustrated in
The history of electric motors reveals that the first machines were axial flow (U.S. Pat. No. 405,858 N. Tesla, 1889). This type of motor was then exploited to the benefit of the radial flow motor until recent development of high-energy magnets such as magnets of NdFeB type called «rare earth» (first publication in 1983) which revived interest in this type of machine.
The characteristic of the axial flow motor is that the direction of the magnetic field is parallel to the axis of rotation of the motor. The conductors through which electric current travels are arranged radially.
The stator is constituted by windings 32 letting the conductors 33 traverse the gap formed by the rotor, and generate torque when they are traversed by electric current. The direction in which the electric current traverses the conductor in the gap relative to the orientation of the field magnetic field created by the magnets of the rotor 31 is essential for the torques generated by each segment of conductor to be added.
Several phases distributed evenly and angularly, activated alternatively produce constant torque irrespective of the angle of position of the rotor relative to the stator. The number of phases of the stator is designated by m. In the majority of cases, m=3. In the case of a three-phase stator, the latter can be assembled in a star or delta, the configuration in a star being the commonest.
Printed circuit technology can be used advantageously to make the stator of an axial-flow electric motor and permanent magnets.
A printed circuit comprises a stack of conductive and insulating layers alternatively. The material used as insulating substrate is generally a composite of epoxide resin reinforced with glass fibre. This substrate supplies the mechanical resistance necessary for supporting stresses generated by the resulting torque. The conductor used is generally a metal such as copper or aluminium.
The conductive layers 41 on the insulating substrate are etched by chemical photoetching to reproduce the preferred patterns. Metallised holes 43 make electric contacts between patterns of two or more conductive layers of the same printed circuit. An insulating varnish 44 is applied on completion of the manufacturing process.
The printed circuit industry currently produces circuits of 2 to 12 layers. The thickness of the layers of conductor used currently varies from 35 micrometers to 140 micrometers. Photoetching technology produces minimal spacing between the tracks, of the order of tens of microns.
The majority of printed circuits produced by the electronics industry is used for assembling discrete electronic components (resistors, condensers, inductors, transistors etc. . . . ) and integrated components (processors, memories, power management circuits etc. . . . ) surface-mounted or traversing.
For this application, the total thickness of the necessary circuit is minimal, of the order of 3 millimeters at most. Consequently, the majority of manufacturing equipment of printed circuits is designed for manufacturing circuits of thickness less then 3 millimeters.
However, in the case of a stator of an axial-flow electric motor this thickness limit can limit the performance of the motor. In fact, for a given intensity of electric current, the less the thickness of the stator, the greater the density of current passing though it. When the density of electric current is excessive, the rise in temperature of the circuit by Joule effect can destroy the latter. If a thickness of the stator greater than 3 millimeters is necessary, the manufacturing equipment for printed circuits should be adapted, which would significantly raise tooling costs.
In this case, use can be made of assembling printed circuits of minimal thickness to produce a stator of greater thickness, as illustrated in
The present invention aims to rectify at least one of these drawbacks.
For this purpose a first aspect of the invention relates to a magnetic 2p poles axial-flow electric motor comprising: a rotor; and a stator with m phases, the stator comprising at least one pair of conductor layers on which conductive tracks constituting the phases of the stator are arranged in semi-phases.
According to an embodiment each semi-phase comprises two sets of conductive tracks; each set of conductive tracks being arranged in a radial configuration between an internal edge of the stator and an external edge of the stator, such that the electric current of a set of conductive tracks of a semi-phase flows from the internal edge of the stator towards the external edge of the stator and the electric current of the other set of conductive tracks of said semi-phase flows from the external edge of the stator towards the internal edge of the stator.
Each set of conductive tracks can comprise one or more conductive tracks.
According to an embodiment one of the sets of conductive tracks of a semi-phase is printed on a layer of a pair of conductor layers and the other set of conductive tracks of said semi-phase is printed on the other layer of said pair of conductor layers.
According to an embodiment the two sets of conductive tracks of a semi-phase are interconnected by connections arranged near the internal and external edges of the stator.
According to an embodiment the two semi-phases of the same phase and of the same pair of conductor layers of the stator are offset relative to each other by rotation of angle
radians.
According to an embodiment two access points of the electric current to the conductive tracks of a semi-phase of a pair of conductor layers of the stator, are offset relative to each other by rotation of angle
radians, each access point being associated with an end of said semi-phase.
According to an embodiment the access points of the electric current of a semi-phase are arranged on the same radius of the stator.
According to an embodiment each access point of the electric current of said semi-phase is offset by a given angle relative to the associated end.
According to an embodiment the access points of the electric current of a semi-phase are radially offset relative to the ends.
According to an embodiment the pairs of conductor layers of the stator are stacked on each other after rotation of 0 or
radians and connected together by the access points of the electric current to the semi-phases now opposite.
According to an embodiment the conductive tracks constituting the phases are assembled in a star, and the points of return are used for injection of the electric current into the stator.
In the following, the embodiments of the invention are described in reference to the attached figures in a known non-limiting manner, in which:
The embodiments of the invention are described in the context of a motor whereof the magnetic excitation field is generated by permanent magnets, as these give the best performances. However, those skilled in the art will recognise that the invention is applicable to others types of magnetic excitation.
To present embodiments of the invention, the arrangement of the poles of a rotor and windings of a stator of an electric motor for a phase of a stator will be described in reference to
The geometric form of the conductive tracks 81 carrying out out-and-back motions can vary. U.S. Pat. No. 3,144,574 proposes especially several geometries which can be used in the context of the invention.
Access by electric current to the semi-phase is done by its ends at point 85 on the internal edge of the stator, as indicated in
A semi-phase 81 uses only half of the surface of available conductor on each layer. It is possible to use a second semi-phase obtained from the first by way of rotation of an angle by
(p being the number of poles), as illustrated in
The phases n and n+1 are separated by an angle of
As a consequence all the semi-phases are almost identical to each other at an angle of rotation.
Each phase of the stator therefore comprises two semi-phases constituted by the conductive tracks 91 (91A and 91B). The terminations for each phase are available at the centre of the circuit between R0 and the internal edge 92 of the stator.
of access points 95A and 95B to the two semi-phases of a phase of the stator is shown on the diagram. The radius can vary from R0 to the internal edge 92 of the stator.
By using a metallised hole for each access point of the electric current 95 of a semi-phase, two circuits can be assembled in parallel. A disadvantage of this assembly is that the greater the number of layers, the less the equivalent resistance of the assembly. This involves considerable supply currents, which can be prohibitive according to the preferred characteristics of the motor and of the power electronics.
To assemble two identical electric circuits in series, a particular embodiment of the invention consists of placing the metallised access holes of the electric current on the conductive tracks 1101 of the semi-phases, as illustrated in
radians relative to each other. They are offset tangentially by an angle 1102 relative to the ends of the semi-phases to prevent the metallised access hole 1104 of the semi-phase 1101 from short-circuiting with the other end 1103 of the same semi-phase connected to the other access point of the electric current 1104. It is evident that it is possible to obtain the others phases of the stator by rotation of the phase shown without short-circuit between the phases by adapting the radius of the access points to the semi-phases for each semi-phase.
In the case where pairs of conductive layers should be stacked inside the same printed circuit, the metallised holes at the periphery and on R0 constituting the intrinsic multi-layer interconnections of the semi-phases would be blind holes. Only the metallised access holes to the semi-phases would be through-holes.
radians of one circuit relative to the other places the metallised holes of access opposite the electric current of the semi-phases such that the latter are connected in series, and the direction of the electric current circulating in each semi-phase lets the torques generated by each semi-phase be added, the arrangements of the tracks of the semi-phases and the poles of the stator being unvarying by rotation of
radians. The metallised holes 1402 let the current enter and exit the set of semi-phases of the two circuits 1401 which constitute a complete phase of the stator. The metallised holes 1402 are called the access points of the phase shown. The point of return 1403 connects the semi-phases together and in this way closes the current loop.
In the case of assembly of two printed circuits, this arrangement therefore allows assembly in series of identical circuits. Tooling costs for manufacturing and logistics are limited.
When a new circuit is added to the stack it can be in series or in parallel according to whether rotation of
relative to the preceding circuit is carried out or not. In the case of assembly of printed circuits, it is possible to obtain different electric configurations with a single type of printed circuit.
If the current is injected at the points of return instead of the access points to the phases, and if the latter are left in open circuit, then only half the windings is used. In this case, the counter-electromotor force for a given speed of rotation is divided by two. This device therefore implements a double-winding dual-speed system. When the rotation speed is low, the current is injected at the access points to the phases. In this case the torque per ampere of current injected will be the greatest. When the rotation speed is high, the current is injected at the points of return, the access points to the phases being left in open circuit. In this case, the counter-electromotor force is divided by two.
In the proposed description, each semi-phase passes through a pole once only to simplify description. In reality, each semi-phase can describe several turns of the stator instead of a single one, as described. Since this other configuration does not change the arrangements of the access points to the semi-phases, it has no influence on the subject of the invention.
As is obvious, and as also results from the above, the invention is not limited to the particular embodiments just described and instead encompasses all variants.
Patent | Priority | Assignee | Title |
Patent | Priority | Assignee | Title |
2970238, | |||
3223868, | |||
3450919, | |||
405858, | |||
4115915, | Jul 31 1975 | General Electric Company | Process for manufacturing motor having windings constructed for automated assembly |
4645961, | Apr 05 1983 | The Charles Stark Draper Laboratory, Inc. | Dynamoelectric machine having a large magnetic gap and flexible printed circuit phase winding |
20060055265, | |||
20060202584, | |||
20110037354, | |||
20110273048, | |||
20120126927, | |||
20120133474, | |||
20120181886, | |||
20150146322, | |||
FR1520439, | |||
WO2004073365, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jul 23 2013 | ELECTRICMOOD | (assignment on the face of the patent) | / | |||
Oct 02 2019 | LIBAULT, DAVID | ELECTRICMOOD | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 050642 | /0533 |
Date | Maintenance Fee Events |
Jul 31 2023 | REM: Maintenance Fee Reminder Mailed. |
Jan 15 2024 | EXP: Patent Expired for Failure to Pay Maintenance Fees. |
Date | Maintenance Schedule |
Dec 10 2022 | 4 years fee payment window open |
Jun 10 2023 | 6 months grace period start (w surcharge) |
Dec 10 2023 | patent expiry (for year 4) |
Dec 10 2025 | 2 years to revive unintentionally abandoned end. (for year 4) |
Dec 10 2026 | 8 years fee payment window open |
Jun 10 2027 | 6 months grace period start (w surcharge) |
Dec 10 2027 | patent expiry (for year 8) |
Dec 10 2029 | 2 years to revive unintentionally abandoned end. (for year 8) |
Dec 10 2030 | 12 years fee payment window open |
Jun 10 2031 | 6 months grace period start (w surcharge) |
Dec 10 2031 | patent expiry (for year 12) |
Dec 10 2033 | 2 years to revive unintentionally abandoned end. (for year 12) |